Prospects of measuring the leptonic CP phase with atmospheric neutrinos

TL;DR

This study explores the potential of atmospheric neutrino experiments with a magnetized iron calorimeter to measure the leptonic CP-violating phase, highlighting the challenges and possible sensitivities in different CP phase scenarios.

Contribution

It demonstrates the feasibility of distinguishing certain CP phases using atmospheric neutrinos despite poor angular resolution, focusing on the energy range where oscillation effects are observable.

Findings

Able to distinguish δ_CP ≈ 0° and 180° at 90% CL

No significant sensitivity for δ_CP ≈ 90° or 270°

Quasi-elastic events dominate at E ~ 1 GeV with good energy resolution

Abstract

We have studied the prospects of measuring the CP violating phase with atmospheric neutrinos at a large magnetized iron calorimeter detector considering the muons (directly measurable) of the neutrino events generated by a MonteCarlo event generator Nuance. The effect of $\theta_{13}$ and $\delta_{CP}$ appears dominantly neither in atmospheric neutrino oscillation nor in solar neutrino oscillation, but appears as subleading in both cases. These are observable in range of $E \sim 1$ GeV for atmospheric neutrino, where solar and atmospheric oscillation couple. In this regime, the quasi-elastic events dominate and the energy resolution is very good, but the angular resolution is very poor. Unlike beam experiments this poor angular resolution acts against its measurements. However, we find that one can be able to distinguish $\delta_{CP}\approx 0^\circ$ and $180^\circ$ at 90% confidence level. We find no significant sensitivity for $\delta_{CP}\approx 90^\circ$ or $270^\circ$.